CN102712983A - Cold-rolled steel plate and method for producing same - Google Patents
Cold-rolled steel plate and method for producing same Download PDFInfo
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- CN102712983A CN102712983A CN201180006238XA CN201180006238A CN102712983A CN 102712983 A CN102712983 A CN 102712983A CN 201180006238X A CN201180006238X A CN 201180006238XA CN 201180006238 A CN201180006238 A CN 201180006238A CN 102712983 A CN102712983 A CN 102712983A
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0236—Cold rolling
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
- C21D8/0273—Final recrystallisation annealing
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
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Abstract
Provided is a cold-rolled steel plate having excellent moldability and shape retention, and outstanding production stability using actual machinery. Also provided is a method for producing same. The composition contains 0.0010 to 0.0030% C, no more than 0.05% C, 0.1 to 0.3% Mn, no more than 0.05% P, no more than 0.02% S, 0.02 to 0.10% Al, no more than 0.005% N, 0.010 to 0.030% Nb, and 0.0010 =<B-11/14N=<0.0050% B, with the remainder made up of iron and inevitable impurities. The average total elongation (Elm) is at least 42%, and average r value (rm) is 1.2 to 1.6. By maintaining post cold-rolling annealing for 30 to 200 sec. at a holding temperature of (820+Nb/15+B-CR) to 860 DEG C according to compression rate CR(%), Nb content (mass ppm) and B content (mass ppm), it is possible to manufacture the cold-rolled steel plate using actual machinery in a stable manner, without pinpoint control of the holding temperature.
Description
Technical field
The backlight chassis etc. that the present invention relates to be suitable as most large-scale LCD TV process the large flat shape parts member, plasticity, shape freezing property and real machine make the cold-rolled steel sheet and the method for manufacture thereof of excellent in stability.
Background technology
In slim liquid crystal TV and OA equipment etc., mostly uses through bending, expansion forming the flat-shaped part that processes shape as main body.For the member that in these parts, uses (material),, component shape is being required in most cases also require Flatness on the basis of degree of finish from viewpoints such as the designability of product and slimmings.Yet, when the platen surface of member (material) is carried out bending, expansion forming, have the tendency of Flatness deterioration.This Flatness deterioration is the phenomenon that produces because of the shape freezing property difference of member (material) when member (material) is carried out drawing, therefore, the steel plate as member (material) is required processibility and shape freezing property simultaneously.
In addition, as the major cause that makes the Flatness variation, the crest line warpage that produces when being well known that bending machining.It is said as one of them, the warpage that produces at crooked end can reduce through the r value that reduces material, established the technology of material being given low r value, low yield strength at present.
For example, disclosing exploitation in the patent documentation 1, to have ys be that the r value of 150MPa, rolling direction is the technology of the cold-rolled steel sheet of 0.67 (the r value of rolling right angle orientation is 1.45).
Disclose in the patent documentation 2 that parallel with the plate face { the 100} face is with { ratio of 111} face is that the good automobile of shape freezing property more than 1.0 is used the ferritic series tole.
In the patent documentation 3; In order to obtain the good ferritic series tole of shape freezing property; Following scheme is disclosed: control 100}＜011＞~ intensity of 223} < 110>orientation group and 112}＜110＞, 554}＜225＞, 111}＜112＞, intensity of 111}＜110＞each orientation, and make rolling direction r value and and the r value of the rectangular direction of rolling direction at least one be below 0.7.
The prior art document
Patent documentation
Patent documentation 1: No. 3532138 communique of Japanese Patent
Patent documentation 2: TOHKEMY 2008-255491 communique
Patent documentation 3: TOHKEMY 2003-55739 communique
Summary of the invention
Invent problem to be solved
But; In patent documentation 1 and 3 in the technology of record, through employing have 100}＜011＞~ { crystal grain of 223}＜110＞orientation can reduce the r value of rolling direction and rolling right angle orientation; But can increase the r value of rolling 45 ° of directions; Therefore, have in a large number 100}＜011＞~ { steel of the crystal grain of 223}＜110＞orientation may damage Flatness after drawing.For example; The backlight chassis that is used for slim LCD TV being implemented make length direction is under the situation of expansion forming of elongated stiffening web shape of rolling 45 ° of directions, exists to produce the crest line warpage on the stiffening web length direction and because near the material inflow of the flange portion the bulging portion produces the problem of backlight chassis warpage.
In addition, in patent documentation 1 ~ 3, disclose the cold rolling rate that reduces cold-rolled steel sheet, particularly made the r value be low to moderate 40% situation, but when being rolled, plate shape variation occurred and make the problem of the Flatness deterioration and so on of final goods with about 40% extremely low cold rolling rate.In addition, though above-mentioned low cold rolling rate makes the raising of shape freezing property, be difficult to make the tole below about 1.0mm.
The ultra-low carbon steel of the tension strain of shaping fracture and fold when therefore, the inventor is conceived to be easy to get high ductibility and is difficult for generation cause drawing.Usually, Ti is that ultra-low carbon steel plates such as IF steel make easily in annealing operation the favourable recrystallize grain of high r value is carried out grain growing, therefore, need hang down the r value.In order to hang down the r value, carrying out recrystallize but crystal grain is difficult for the low temperature of growth anneals down, therefore, need, soaking temperature control annealing conditions under only demonstrating several degrees centigrade the condition of variation at most.But in real machine, therefore the soaking temperature material different of setting during annealing, exists soaking temperature to change tens of degrees centigrade situation approximately successively through continuous annealing apparatus, is difficult to soaking temperature is controlled at several degrees centigrade with interior scope.Therefore, there is following problem: under the temperature higher, anneal, thereby can not realize low r value than target temperature.In patent documentation 1 ~ 3, also there is same problem, for the condition of annealing temperature, though on the books, there is not consideration accurately to control the difficulty of annealing temperature.
In view of the foregoing; The objective of the invention is to solve above-mentioned prior art problems, and provide can carry out that deep-draw processing, bending machining, bulging are processing, that can guarantee the desired shape of large component, plasticity and shape freezing property is good and real machine is made the cold-rolled steel sheet and the method for manufacture thereof of excellent in stability.
The method that is used to deal with problems
In order to address the above problem, the contriver has carried out deep research repeatedly.As a result, find following aspect.At first, even carry out processibility and the high shape freezing property that complicated processing can not produce warpage yet, importantly make the annealed sheet after cold rolling control the r value down at the state that keeps high ductibility in order to take into account.That is,, can guarantee that deep-draw processing, bulging add the processibility in man-hour, and can guarantee the desired shape of parts through increasing average elongation.And then; R value through reducing rolling direction, rolling right angle orientation and rolling 45 ° of these three directions of direction also makes average r value in specialized range; Implementing to make length direction is also can prevent warpage under the situation of expansion forming of elongated stiffening web shape of rolling 45 ° of directions; Can suppress to process the back and produce resilience, warpage, thereby can guarantee shape freezing property.
Through measuring the soaking temperature scope that is provided with in the annealing operation, can under the situation that need not accurately control soaking temperature, stably make according to rolling rate, Nb amount and B.
The present invention is based on above-mentioned opinion and accomplish, its purport is following.
(1) a kind of cold-rolled steel sheet; It is characterized in that; Has following composition: in quality %; Below C:0.0010 ~ 0.0030%, Si:0.05%, Mn:0.1 ~ 0.3%, below the P:0.05%, below the S:0.02%, Al:0.02 ~ 0.10%, below the N:0.005%, Nb:0.010 ~ 0.030%, B:0.0010≤B-11/14 * N≤0.0050%, surplus is iron and unavoidable impurities
And, the average elongation (El that representes by following (a) formula
m) be more than 42%, the average r value (r that representes by following (b) formula
m) be 1.2 ~ 1.6,
Average elongation El
m=(El
L+ 2El
D+ El
C)/4 ... (a)
Average r value r
m=(r
L+ 2r
D+ r
C)/4 ... (b)
At this, El
L: the elongation of rolling direction, El
D: the elongation of rolling 45 ° of directions, El
C: the elongation of rolling right angle orientation, r
L: the r value of rolling direction, r
D: the r value of rolling 45 ° of directions, r
C: the r value of rolling right angle orientation.
(2) like above-mentioned (1) described cold-rolled steel sheet; It is characterized in that; In quality %, also contain Ti:0.005% ~ 0.020%, and replace above-mentioned B:0.0010≤B-11/14 * N≤0.0050% with B:0.0015＜B-11 * (| N/14-Ti/48|+ (N/14-Ti/48))/2≤0.0050%.
(3) a kind of method of manufacture of cold-rolled steel sheet is characterized in that, the steel billet of above-mentioned (1) or above-mentioned (2) said composition is heated under the Heating temperature more than 1150 ℃; Then, carry out under the finishing temperature more than 880 ℃, finishing the hot rolling of finish to gauge, batching below 700 ℃; Implement pickling; Carry out cold rollingly with 55 ~ 80% rolling rate, then, measure (quality ppm) with B according to this rolling rate CR (%), Nb amount (quality ppm); Carry out under the soaking temperature of (820+Nb/15+B-CR) ~ 860 ℃, keeping 30 ~ 200 seconds annealing, then cool off.
Need to prove that in this manual, %, the ppm of the composition of expression steel are quality %, quality ppm.In addition, also comprise surface treatments such as cold-rolled steel sheet being implemented electro-galvanizing, pot galvanize as the cold-rolled steel sheet of object of the present invention and the steel plate that obtains.And, also comprise the steel plate that has applied tunicle on this basis through chemical conversion processing etc.
In addition, steel plate of the present invention backlight chassis, panel of refrigerator, air-conditioner outdoor unit etc. that can be widely used as large-scale TV have planar portions and have implemented the general member of the household electrical appliances purposes of bending, bulging, slight deep-draw processing etc.And then, if use the present invention, then for example can utilize thickness of slab to make the above backlight chassis of about 650mm * about 500mm (32V type) for the steel plate of 0.8mm.
The invention effect
According to the present invention, can access the plasticity and the good cold-rolled steel sheet of shape freezing property that can carry out deep-draw processing, bending machining, bulging processing.And, can under the situation of the soaking temperature that need not accurately control when annealing, utilize real machine stably to make plasticity and the good cold-rolled steel sheet of shape freezing property.Thus, the desired writing board shape of large component can be guaranteed, thereby the members such as backlight chassis of large-scale LCD TV can be made.
Description of drawings
Fig. 1 is the figure of the relation of expression cold rolling rate (rolling rate) CR and soaking temperature and performance.
Fig. 2 is the figure of the relation of expression Nb (quality ppm)/15+B (quality ppm) and soaking temperature and performance.
Fig. 3 is the figure that the soaking temperature in when annealing expression is given the influence that average r value brings.
Fig. 4 is expression as the soaking temperature in when annealing figure of AT-ATO and the relation of average r value of proper index whether.
Fig. 5 is expression as the soaking temperature in when annealing figure of the relation of AT-ATO and the average elongation of proper index whether.
Embodiment
Below, the present invention is elaborated.At first, the chemical ingredients to steel plate of the present invention describes.Need to prove that in the explanation below, content %, the ppm of composition element all represent quality %, quality ppm.
C：0.0010~0.0030%
C has the effect that reduces the r value, and therefore, from the viewpoint of low r value, preferred heavy addition is more than 0.0010%.But excessive interpolation can bring the tension strain that produces the reason of fold when becoming drawing, and owing to the caused dispersion-strengthened steel plate high strength that makes of the formation of solution strengthening, carbide, elongation reduces.Therefore, making C is more than 0.0010% and below 0.0030%.
Below the Si:0.05%
Si is the high element of solution strengthening ability, improves ys and significantly reduces elongation.Therefore, making Si is below 0.05%.
Mn：0.1~0.3%
Mn forms sulfide and improves hot short element.In order to obtain this effect, need to add more than 0.1%.On the other hand,, make the ys raising and make the ductility variation, therefore, make to be limited to 0.3% owing to be the high element of solution strengthening ability.
Below the P:0.05%
P is the solution strengthening element, ys is improved and makes the ductility variation.Therefore, making P is below 0.05%.
Below the S:0.02%
S forms sulfide in the stage of hot-rolled sheet, becomes the reason that makes the ductility variation.Therefore, making S is below 0.02%.
Al：0.02~0.10%
The avidity of Al and N is strong, has the solid solution N amount reduction when making cold rolling process, the effect of inhibition age hardening.In addition, the fine tendency of separating out of the AlN that separates out is higher, in annealing operation, suppresses grain growing.In order to obtain these effects, need to add more than 0.02%.But excessive interpolation causes manufacturing cost to raise, and during hot rolling, making from austenite phase transformation is that ferritic temperature raises, and therefore, is difficult to accomplish in the austenitic area rolling.Therefore, need make A1 is below 0.10%.
Below the N:0.005%
N contains sometimes in a large number, and solid solution in steel becomes the reason of tension strain.Therefore, making N is below 0.005%.
Nb：0.010~0.030%
Nb suppresses tension strain with the form fix of solid solution C with precipitate.And then, also have precipitate and be fine the separating out of NbC and the tendency of grain growing when suppressing to anneal.In order to obtain these effects, need to add more than 0.010%.But, under the situation of excessive interpolation, recrystallization temperature is excessively raise.In addition, cause cost to increase, therefore, the upper limit is set at 0.030%.
B:0.0010≤B-11/14 * N≤0.0050% (under the situation of adding Ti, 0.0015＜B-11 * (| N/14-Ti/48|+ (N/14-Ti/48))/2≤0.0050%)
B is in the present invention as the element of essential condition, exists with the form of solid solution B in steel through making it, can suppress ferritic grain growing in the annealing process after cold rolling, even under high soaking temperature, also can control the r value.In order to obtain this effect, need when hot rolling, at high temperature separate out BN and have the solid solution B more than 0.0010% afterwards.But, during excessive interpolation, form precipitate with C, elongation is reduced.For the above-mentioned reasons, be set at 0.0010≤B-11/14 * N≤0.0050%.Be preferably 0.0015＜B-11/14 * N≤0.0050%.
And then under the situation of adding Ti, the TiC thicker than NbC separates out, and therefore the grain growing property raising during annealing, need make the solid solution B amount with the effect that suppresses grain growing surpass 0.0015%.But, during excessive interpolation, form precipitate with C, elongation is reduced.For the foregoing reasons, adopt 0.0015%＜B-11 * (| N/14-Ti/48|+ (N/14-Ti/48))/2≤0.0050% to replace the relational expression of above-mentioned B:0.0010≤B-11/14 * N≤0.0050%.Be preferably 0.0020%≤B-11 * (| N/14-Ti/48|+ (N/14-Ti/48))/2≤0.0050%.
In the present invention, on the basis of above-mentioned element, can the scope 0.005% ~ 0.020% contain Ti with following purpose.
The avidity of Ti and N is strong, at high temperature forms precipitate, has the solution strengthening that suppresses solid solution N, by the fine dispersion-strengthened effect that causes of separating out of AlN.In addition, also can under the situation that will improve elongation especially, add.In order to bring into play these effects, preferably add more than 0.005%.But excessive interpolation can promote separating out of TiC, not only reduce the effect of the grain growing in inhibition when annealing that brings by NbC, and cause manufacturing cost to raise, therefore, make when adding on be limited to 0.020%.
Composition except that above-mentioned is made up of iron and unavoidable impurities.As unavoidable impurities, for example can enumerate: the Cu below 0.05%, the Cr that sneak into easily, and the Sn below 0.01% in addition, Mo, W, V, Ni etc. from waste material.
With regard to steel plate of the present invention, making the average elongation of obtaining through following (a) formula is more than 42%.Elongation and plasticity have good dependency, and elongation is big more, for example can expansion forming to high more.Therefore, the elongation that needs is the bigger the better, and increases to more than 42% through making average elongation, can carry out deep-draw processing, bulging processing, thereby can guarantee the desired shape of parts.
Need to prove that average percentage of total elongation can be measured through following method and obtain.On rolling direction, rolling 45 ° of directions and rolling right angle orientation, downcut JIS5 tension test sheet respectively, carry out tension test according to JIS Z 2241.Then, obtain through following (a) formula.
Average elongation El
m=(El
L+ 2El
D+ El
C)/4 ... (a)
At this, El
L: the elongation of rolling direction, El
D: the elongation of rolling 45 ° of directions, El
C: the elongation of rolling right angle orientation.
For steel plate of the present invention, making the average r value of obtaining through following (b) formula is 1.2 ~ 1.6.The warpage that produces behind r value and bending forming, the expansion forming has dependency.In bending forming, the r value of bending direction increases, and thus, obviously produces saddle type warpage along wiggle.In addition, in expansion forming, through using high r value material, flow into from the material of the flange part around the bulging portion and to become significantly, produce unrelieved stress and distortion at flange part.Therefore, in order to improve the shape freezing property after the drawing through low r value, in the present invention, making average r value is below 1.6.On the other hand, the low r value meeting of over-drastic extremely reduces elongation, therefore, makes the following of average r value be limited to 1.2.
Need to prove that average r value can be measured through following method and obtain.On rolling direction, rolling 45 ° of directions and rolling right angle orientation, downcut JIS5 tension test sheet respectively, the prestrain with 15% is carried out the plastic strain ratio test according to JIS Z 2254.Then, obtain through following (b) formula.
Average r value r
m=(r
L+ 2r
D+ r
C)/4 ... (b)
At this, r
L: the r value of rolling direction, r
D: the r value of rolling 45 ° of directions, r
C: the r value of rolling right angle orientation.
In addition; For example; The backlight chassis that is used for slim LCD TV being implemented make length direction is under the situation of expansion forming of elongated stiffening web shape of rolling 45 ° of directions; In the crest line warpage that produces on the stiffening web length direction and because of near the material of the flange portion the bulging portion flows into the warpage of the backlight chassis that produces, when the r of rolling 45 ° of directions value is high, become big.Therefore; Importantly reduce the r value of rolling direction, rolling right angle orientation and rolling 45 ° of these three directions of direction; Preferably on average r value was 1.2 ~ 1.6 basis, preferably the maximum r value in rolling direction, rolling right angle orientation and these three directions of rolling 45 ° of directions was less than 2.0.
Below, the method for manufacture of cold-rolled steel sheet of the present invention is described.
In the present invention, the steel billet that will have above-mentioned composition heats under the Heating temperature more than 1150 ℃, then; Carry out under the finishing temperature more than 880 ℃, finishing the hot rolling of finish to gauge, batching below 700 ℃, implement pickling; Then carry out cold rollingly, then, measure (quality ppm) with B according to this rolling rate CR (%), Nb amount (quality ppm) with 55 ~ 80% rolling rate; Carry out under the soaking temperature of (820+Nb/15+B-CR) ~ 860 ℃, keeping 30 ~ 200 seconds annealing; Then cool off, thus, can access high elongation rate, low r value.
Heating temperature: more than 1150 ℃
The steel of having adjusted composition is heated to more than 1150 ℃ and makes the precipitate solid solution.Pine for being lower than 1150 ℃ add, N, C are residual under the state of not solid solution, are batching when handling or during annealing, and carbide, nitride be fine separating out and can't give full play to the effect of the grain growing when suppressing annealing not.Therefore, Heating temperature is high more good more, is more than 1150 ℃, is preferably more than 1200 ℃.But, when excessively heating, on the steel surface, generate thick oxide debris, thereby increase the cost of cleanup acid treatment, therefore, be preferably below 1300 ℃.
Finishing temperature: more than 880 ℃
Then carry out hot rolling.On the finish to gauge frame when finish to gauge, be rolled when need be in the austenitic area single-phase.Under the situation about being rolled in austenite and ferritic two-phase region, bigger variation takes place with phase transformation in rolling load, therefore, is difficult to the load of controlled rolling frame, might cause the plate fracture.In addition, rollingly can promote the residual of non-recrystallization in that ferrite area is monophasic, thereby ensuing rolling load in cold rolling is excessively increased, possibly cause manufacturing cost to raise thus.For the above-mentioned reasons, finishing temperature is set at more than 880 ℃, carries out finish to gauge in the austenitic area when single-phase.Need to prove, when finishing temperature is too high, the oxide debris thickening, the cost of cleanup acid treatment increases, and therefore, preferably is below 950 ℃.
Preferably after finish to gauge, carry out water cooling.Knownly before cold rolling, make C, N solid solution and reduce the r value, in order to suppress separating out of C, N, and the grain growing when suppressing to anneal in order to make the carbide of separating out, nitride micro refinement, preferably carry out above-mentioned cooling.
Coiling temperature: below 700 ℃
As the final operation of hot rolled, below 700 ℃ coils of hot rolled is being batched.When coiling temperature surpassed 700 ℃, Al, Nb, Ti at high temperature formed carbide, nitride, from guaranteeing that it is not preferred bringing the cold rolling preceding solid solution C of influence, the viewpoint of solid solution N to reduction r value.Need to prove that coiling temperature is crossed when hanging down, therefore the winding form variation of coiled material, preferably is more than 400 ℃.
Rolling rate (CR) when cold rolling: 55 ~ 80%
Utilize usual method that hot-rolled sheet is carried out pickling.Then, to be rolled rate (CR) be more than 55% and 80% below cold rolling, be configured as the thickness of slab of expectation.Rolling rate (CR) was less than 55% o'clock, and tissue forms mixing crystal grain and ductility is extremely reduced.On the other hand, rolling rate (CR) is higher than at 80% o'clock, and the annealing back is prone to form to reducing the disadvantageous texture of r value.
Soaking temperature: (820+Nb/15+B-CR) ~ 860 ° C, hold-time: 30 ~ 200 seconds
Then,, measure (quality ppm) with B, under the soaking temperature of the scope of (820+Nb/15+B-CR) ~ 860 ℃, kept 30 ~ 200 seconds according to rolling rate CR (%), Nb amount (quality ppm) as annealing operation.Cool off then.
In annealing operation, through recrystallize the strain because of cold rolling introducing is disappeared, thereby make softization of steel plate.Rolling rate (CR) is high more, and particularly the amount of Nb, B is few more to add element, and the temperature of accomplishing recrystallize is low more.Therefore, in order to prevent to reduce because of the residual elongation that makes of non-recrystallization tissue, need make soaking temperature is more than (820+Nb/15+B-CR).The qualification reason of this soaking temperature describes in the back.On the other hand, during the recrystallization temperature that exceedingly raises, except manufacturing cost raises; Ferritic phase becomes austenite; And then when cooling from austenite to ferrite transformation, makes the excessive tissue miniaturization thus and high strength takes place, and elongation decreases.Therefore, need make soaking temperature is below 860 ℃.
In addition, the soaking hold-time is when too short, the non-recrystallization tissue residue, and when long, grain growing is excessively carried out and the r value is increased.Therefore, need make the hold-time is more than 30 seconds and below 200 seconds.In addition, the cooling after the soaking prevents that the r value from increasing because of the over-drastic grain growing, therefore, preferably cools off with the speed more than 3 ℃/second.
At this, the soaking temperature to will anneal the time is set at (820+Nb/15+B-CR) above reason and describes particularly.Usually, when improving rolling rate, the motivating force of recrystallize increases, and the temperature (below, be called recrystallization temperature) of accomplishing recrystallize during annealing moves to low temperature side.On the other hand, when the Nb that increase is added, the amount of B, recrystallize significantly is suppressed, and recrystallization temperature moves to high temperature side.According to the inventor's experiment, recrystallization temperature and rolling rate (CR), the Nb amount, the B measurer that add have correlationship.Fig. 1 is the figure of the relation of the rolling rate of expression (CR) and soaking temperature and performance, and Fig. 2 is the figure of the relation of expression Nb (quality ppm)/15+B (quality ppm) and soaking temperature and performance.At this, supplying the chemical constitution of examination material among Fig. 1 is Nb:150ppm, B:30ppm, and rolling rate (CR) is 70% among Fig. 2.The soaking temperature during except that annealing, be the characteristic value of the annealed sheet of making within the scope of the invention.In addition, among each figure, be 42% or more and average r value is that 1.2 ~ 1.6 situation note does zero with average elongation, with the situation that does not satisfy above-mentioned value remember work *.Straight line among each figure be soaking temperature=(820+Nb/15+B-CR) (℃) straight line, and be with zero with the * good boundary line that separates.According to Fig. 1 and Fig. 2, the soaking temperature in when annealing be (820+Nb/15+B-CR) (℃) when above, can make average elongation and be more than 42% and on average the r value be 1.2 ~ 1.6 plasticity and the good cold-rolled steel sheet of shape freezing property.Soaking temperature during for the above-mentioned reasons, with annealing is set at more than (820+Nb/15+B-CR).
Need to prove that when embodiment of the present invention, melting method can suitably use common converter process, electric furnace process etc.After steel after the melting is cast as steel billet, directly implement hot rolling or hot rolling is heated, implemented then in the cooling back under above-mentioned Heating temperature.In hot rolling, after carrying out finish to gauge under the above-mentioned finishing temperature, under above-mentioned coiling temperature, batch.Speed of cooling after the finish to gauge till batch does not have special stipulation, as long as there is the above speed of cooling of air cooling promptly enough.In addition, can carry out the chilling more than 100 ℃/second as required.Then, after common pickling, implement above-mentioned cold rolling.In the annealing (heating-all thermal treatment-cooling), under above-mentioned condition, heat ~ cool off.In order to improve erosion resistance, can near 480 ℃, carry out plating as required through pot galvanize.In addition, behind the plating, also can reheat to 500 ℃ more than and make coating alloying.Perhaps, can be employed in the thermal history that cooling keeps etc. midway.And then, can carry out temper rolling or leveling with the elongation below 2% as required.In addition, do not implement under the situation of plating midway, can carry out electro-galvanizing etc. in annealing.And then, can also on cold-rolled steel sheet and coated steel sheet, give tunicle through chemical conversion processing etc.As above make cold-rolled steel sheet of the present invention.
(embodiment 1)
Embodiments of the invention are described.Steel to having chemical constitution shown in the table 1 carries out melting, under table 2, the creating conditions shown in 3, makes to supply the examination material.In the table 1, solid solution B is meant the value of B-11/14 * N.But adding under the situation of Ti, be meant the value of B-11 * (| N/14-Ti/48|+ (N/14-Ti/48))/2.In addition, be to be designated as 0 under the situation below 0 in the value of calculating.The details of creating conditions is following.At first, in hot-rolled process, will fuse steel and heat 1 hour down, carry out roughing, finish to gauge at 1250 ℃.Table 2, the FT shown in 3, CT are respectively finishing temperature and coiling temperature.The thickness of slab of hot-rolled sheet is 2.0 ~ 3.5mm.Then, before cold rolling process, carry out pickling, at room temperature being rolling to thickness of slab is 0.6 ~ 1.0mm.Then,, be heated to each soaking temperature with 20 ℃/second rate of heating as annealing operation, under soaking temperature, keep 30 ~ 200 seconds after, be cooled to room temperature with 20 ℃/second speed of cooling.Table 2, the CR shown in 3, AT, ATO represent cold rolling rolling rate, soaking temperature, (820+Nb/15+B-CR) respectively.After the annealing, carry out elongation and be 1.0% temper rolling, obtain supplying the examination material.For the confession examination material that obtains, investigation average elongation (El
m) and average r value (r
m).Need to prove, for average elongation (El
m) and average r value (r
m); On the rolling direction (L direction) that supplies the examination material, rolling 45 ° of directions (D direction), rolling right angle orientation (C direction), downcut JIS5 tension test sheet respectively; Elongation is through measuring according to the tension test of JIS Z 2241, and the r value is measured with 15% prestrain according to JIS Z2254 as stated.Then, reach (b) formula, obtain average elongation (El through above-mentioned (a) formula
m) and average r value (r
m).The result who obtains is shown among Fig. 3, Fig. 4, Fig. 5, and the result is shown in table 2, the table 3 with creating conditions in the lump.
Table 2
In example of the present invention, average elongation is more than 42%, and average r value is 1.2 ~ 1.6, and plasticity and shape freezing property are good.In addition; By the label 32 ~ 35 of table 2 and table 3 41 ~ 44 create conditions and mechanical characteristics can be known, in example of the present invention, demonstrate the r value and be 1.2 ~ 1.6 and elongation be that the soaking temperature scope of the value more than 42% is 800 ℃ ~ 850 ℃; Relative with it; In comparative example, when the few composition system of solid solution B amount, do not observe demonstrate the r value be 1.2 ~ 1.6 and elongation be the soaking temperature of the value more than 42%.Therefore confirmed, in example of the present invention, even high temperature annealing also can obtain low r value and high elongation rate and have good real machine making stability.
Fig. 3 is the figure that the soaking temperature in when annealing expression is given the influence that average r value brings.In the many examples of the present invention of solid solution B amount, though the soaking temperature during annealing in higher range, average r value also can reach 1.2 ~ 1.6.
Fig. 4 is expression as the soaking temperature in when annealing figure of AT-ATO and the relation of average r value of proper index whether.When AT-ATO was negative, soaking temperature was improper, and recrystallize can not fully carry out, the result, and average r value is less than 1.2.
Fig. 5 is expression as the soaking temperature in when annealing figure of the relation of AT-ATO and the average elongation of proper index whether.When AT-ATO was negative, soaking temperature was improper, and recrystallize can not fully carry out, the result, and average elongation is less than 42%.
Claims (3)
1. a cold-rolled steel sheet is characterized in that,
Has following composition: in quality %; Below C:0.0010 ~ 0.0030%, Si:0.05%, Mn:0.1 ~ 0.3%, below the P:0.05%, below the S:0.02%, Al:0.02 ~ 0.10%, below the N:0.005%, Nb:0.010 ~ 0.030%, B:0.0010≤B-11/14 * N≤0.0050%; Surplus is iron and unavoidable impurities
And, the average elongation (El that representes by following (a) formula
m) be more than 42%, the average r value (r that representes by following (b) formula
m) be 1.2 ~ 1.6,
Average elongation El
m=(El
L+ 2El
D+ El
C)/4 ... (a)
Average r value r
m=(r
L+ 2r
D+ r
C)/4 ... (b)
At this, El
L: the elongation of rolling direction, El
D: the elongation of rolling 45 ° of directions, El
C: the elongation of rolling right angle orientation, r
L: the r value of rolling direction, r
D: the r value of rolling 45 ° of directions, r
C: the r value of rolling right angle orientation.
2. cold-rolled steel sheet as claimed in claim 1; It is characterized in that; In quality %, also contain Ti:0.005% ~ 0.020%, and replace said B:0.0010≤B-11/14 * N≤0.0050% with B:0.0015＜B-11 * (| N/14-Ti/48|+ (N/14-Ti/48))/2≤0.0050%.
3. the method for manufacture of a cold-rolled steel sheet is characterized in that, the steel billet of claim 1 or 2 said compositions is heated under the Heating temperature more than 1150 ℃; Then, carry out under the finishing temperature more than 880 ℃, finishing the hot rolling of finish to gauge, batching below 700 ℃; Implement pickling; Carry out cold rollingly with 55 ~ 80% rolling rate, then, measure (quality ppm) with B according to this rolling rate CR (%), Nb amount (quality ppm); Carry out under the soaking temperature of (820+Nb/15+B-CR) ~ 860 ℃, keeping 30 ~ 200 seconds annealing, then cool off.
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| JP2010006554A JP5056863B2 (en) | 2010-01-15 | 2010-01-15 | Cold rolled steel sheet and method for producing the same |
| JP2010-006554 | 2010-01-15 | ||
| PCT/JP2011/050586 WO2011087107A1 (en) | 2010-01-15 | 2011-01-07 | Cold-rolled steel plate and method for producing same |
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| JP (1) | JP5056863B2 (en) |
| KR (1) | KR101463667B1 (en) |
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| CN106029926A (en) * | 2014-02-25 | 2016-10-12 | 杰富意钢铁株式会社 | Steel plate for crown cap, method for manufacturing same, and crown cap |
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| DE102011056847B4 (en) * | 2011-12-22 | 2014-04-10 | Thyssenkrupp Rasselstein Gmbh | Steel sheet for use as a packaging steel and process for the production of a packaging steel |
| KR102322713B1 (en) * | 2019-12-19 | 2021-11-04 | 주식회사 포스코 | Cold-rolled steel sheet having excellent heat-resistance and formability and manufacturing method therof |
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2010
- 2010-01-15 JP JP2010006554A patent/JP5056863B2/en active Active
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2011
- 2011-01-07 CN CN201180006238.XA patent/CN102712983B/en active Active
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- 2011-01-07 WO PCT/JP2011/050586 patent/WO2011087107A1/en active Application Filing
- 2011-01-07 KR KR1020127019805A patent/KR101463667B1/en active IP Right Grant
- 2011-01-07 MX MX2012008181A patent/MX354951B/en active IP Right Grant
- 2011-01-13 TW TW100101212A patent/TWI429757B/en active
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| JPH02156023A (en) * | 1988-12-09 | 1990-06-15 | Sumitomo Metal Ind Ltd | Manufacture of cold rolled steel sheet having good formability |
| WO1996026300A1 (en) * | 1995-02-23 | 1996-08-29 | Nippon Steel Corporation | Cold-rolled steel sheet and hot-dipped galvanized steel sheet excellent in uniform workability, and process for producing the sheets |
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| WO2010010964A1 (en) * | 2008-07-22 | 2010-01-28 | Ｊｆｅスチール株式会社 | Cold-rolled steel sheet, process for production of same, and backlight chassis |
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| CN106029926B (en) * | 2014-02-25 | 2018-10-02 | 杰富意钢铁株式会社 | Bottle cap steel plate and its manufacturing method and bottle cap |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2011144428A (en) | 2011-07-28 |
| WO2011087107A1 (en) | 2011-07-21 |
| JP5056863B2 (en) | 2012-10-24 |
| KR101463667B1 (en) | 2014-11-19 |
| KR20120099144A (en) | 2012-09-06 |
| TWI429757B (en) | 2014-03-11 |
| MY155323A (en) | 2015-09-30 |
| CN102712983B (en) | 2014-03-12 |
| MX2012008181A (en) | 2012-08-03 |
| TW201139697A (en) | 2011-11-16 |
| MX354951B (en) | 2018-03-27 |
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